The present disclosure relates, in general, to electrical conductors, and, more specifically, to shielded electrical power supply cables.
Internal electrical wiring in residential homes for 15 ampere A.C. power supply electrical service has for years been standardized as 14-2G type NM-B sheathed cable. This sheathed cable consists of three 14 gage solid conductors, with the line and neutral conductors individually insulated and disposed in a parallel flat lay on opposite sides of an insulated ground conductor. This cable construction has several features which minimize magnetic field interaction and damping of mechanical vibrations generated by the 60 Hz North America electrical power carrier frequency. Such features include the spacing apart of the current carrying line and the neutral conductors, the use of relatively stiff, solid 14 AWG conductors, and relatively stiff insulation and cable jacket. These features combine to minimize interaction of the magnetic fields and resist the attracting and repelling forces caused by the magnetic fields associated with the two closely spaced line and neutral conductors.
Conversely, typical A.C. power supply cords for electrical appliances, such as audio amplifiers, preamplifiers, etc., have a construction that is optimized for maximum flexibility and durability in potentially high flex cycle applications. Such power supply cords have close conductor spacing geometry, which increases magnetic interaction between the line and neutral current carrying conductors. Such cords also typically use stranded conductors and soft fillers, such as cotton and paper, between the conductors and the outer jacket material. All of these features compromise the self-damping quality of the power supply cord thereby leading to increased vibration of the individual conductors due to the interacting magnetic fields generated by the current carrying conductors. The movement of the conductors due to magnetic field interaction is also enhanced by the use of the soft fillers and the relatively flexible outer jacket.
The inventor previously devised a power cable described in U.S. Pat. No. 5,864,094, which is particularly suited for use in supplying electrical power to audio equipment, since it has reduced magnetic field interactions between the line and neutral conductors, less vibration of the individual current carrying conductors, has a solidly filled construction to minimize any movement of the individual conducts within the cable, and has a reduced inductance.
It would still be desirable to provide a cable for electrical applications including supplying electrical power to audio equipment or acting as audio speaker cable which meets the functionality of the inventors' previously devised cable, but which has different line and neutral conductor configurations to further optimize current handling characteristics.